永磁游标直线电机磁场解析计算

永磁游标直线电机(linear permanent magnet vernier motor,LPMVM)依靠磁场调制原理工作,其电枢开槽引起气隙磁导变化,为考虑齿槽效应的影响,将其气隙磁场等效为无槽气隙磁场与有槽时气隙相对磁导函数共同作用结果。用气隙磁导波法分析其基本工作机理,给出结构关系式。用分层模型法建立无槽LPMVM求解场域矢量磁位解析模型,推导出各区域磁场解析表达式。结合气隙相对磁导函数建立考虑齿槽效应时的LPMVM磁场解析模型,计算出考虑齿槽效应时气隙磁密分布曲线。解析解与有限元解结果表明:无槽时气隙磁密在切向分量和法向分量计算准确,考虑齿槽效应后基于气隙相对磁导函数的磁场解析模型适用于求解气隙磁密法向分量,且主要谐波磁场与永磁体极对数和电枢绕组极对数有关。     

定子开槽永磁同步电机气隙比磁导解析计算

采用镜像和保角变换相结合的方法计算定子开槽永磁同步电机的气隙比磁导。以光滑转子铁磁表面为镜面,将定子开槽永磁同步电机气隙原像及其镜像作为解析模型,经过多次保角变换得到气隙比磁导解析公式。解析模型考虑了齿槽之间的影响、定子开槽对气隙磁场径向分量和切向分量的影响,解析公式可用于定子开槽永磁同步电机的励磁磁场、电枢反应磁场、电磁力和齿槽转矩。在解析模型的基础上,对某定子开槽永磁同步电机单个齿槽指定路径上和气隙区域内气隙比磁导进行求解,与有限元结果相比较,表明了所提解析方法的准确性。     

无槽永磁直线同步电动机的稳态分析

建立无槽式永磁直线同步电动机分层解析模型,由于电机等效气隙较长、漏磁较大,采用磁化电流法等效永磁体电流密度,电枢电流按实际情况考虑。以矢量磁位作为求解变量得到励磁磁场和电枢反应磁场的二维解。在此基础上求电机的电磁参数:气隙磁密、电磁推力、电感和电势等。进一步分析气隙长度对电机磁场的影响,用有限元法验证解析结果,两种方法所得结果吻合较好,表明该解析法行之有效。     

电励磁双凸极发电机偏心特性研究

针对电励磁双凸极发电机静态偏心故障,首先对于发电机的气隙长度进行了等效解析建模,并对静偏心程度与磁链、电磁转矩以及气隙磁密等重要特性的关系进行了理论推导。然后,通过Ansys有限元建立12/8三相电励磁双凸极发电机的2D有限元模型,并对电磁信号理论分析结果进行验证。最后,利用Workbench中耦合电磁、模态与谐响应分析模块对发电机的径向振动信号进行有限元仿真。研究结果表明,仿真结果与理论分析结果基本吻合,证明静偏心故障中偏心率对于电励磁双凸极发电机性能具有一定的影响,为后续其静偏心故障诊断提供理论基础。     

Experimental study on harmonics reduction effects of damper windings in a synchronous generator

With the recent development of power electronics technology, thyristor-controlled equipment has largely been introduced to the electric power system. These devices generate harmonics that cause voltage distortion and undesirable effects on the power system components. On the other hand, the damper windings of synchronous generators basically are designed to reduce harmonics as well as to damp out system oscillations. However, up to now, the effects of damper windings on harmonics have not been clarified fully in a quantitative way. In this paper, the results of experimental study on the harmonics reduction effect of damper windings have been presented. A specially designed 6-kVA generator was connected to an infinite-bus system to investigate the characteristics of damper windings. A new method to measure induced voltages between damper bars, damper bar currents and air-gap flux densities in the tested generator was established. By comparing these measurements with and without the presence of damper windings, the effect of damper windings was quantified. Thus the reduction effects of the damper windings on slot ripples and harmonics caused by armature current mmf were investigated and were made clearer than before by the proposed method.     

轴向磁通永磁同步电机气隙磁场解析计算

针对双定子单转子表面嵌入式轴向磁通永磁同步电机的气隙磁场进行了解析研究。建立了气隙磁场的解析模型,将轴向磁通电机等效成直线电机并建立了等效面电流模型来求解空载工况下的气隙磁场。根据电磁场理论中的唯一性定理,给出了满足泊松方程的边界条件,并将分离变量法应用于泊松方程的解析解来计算电机三相定子电枢绕组作用下的气隙磁场。通过将空载下的气隙磁场与电枢绕组作用下的磁场叠加来预测电机负载工况下的气隙磁场。最后用三维有限元仿真计算结果与解析模型的计算结果相比较,证明了解析法可以有效地计算轴向磁通电机的气隙磁场,为轴向磁通永磁同步电机的解析分析和优化设计提供了基本手段。     

A new self-excitation scheme for three-phase synchronous generators

A new self-excitation scheme has been developed for three-phase synchronous generators. The generator that uses this scheme behaves as a flat-compound machine without automatic voltage regulators. The stator of the generator is provided with an armature winding that generates the fundamental and 2nd-harmonic mmfs. The rotor is equipped with a field winding and a harmonic winding. The harmonic winding is magnetically coupled to the 2nd-harmonic mmf produced by the armature winding. The current flows in the stator armature winding by way of a three-phase set of capacitors connected across its three-phase terminals and the ac voltage is induced in the rotor harmonic winding due to the armature 2nd-harmonic mmf. By connecting the harmonic winding to the field winding through a rectifier circuit, self-excitation of the generator is obtained. This excitation scheme is both self-excited and brushless, and no exciter is required. Additionally, voltage regulation due to load variation can be improved by connecting suitable capacitors. In this paper the operating principle and circuit configuration of the generator are explained and the experimental results using a 1-kVA prototype machine are shown. The generator characteristics are theoretically clarified by approximate analysis, and appropriateness of the theory and the usefulness of the proposed scheme are experimentally confirmed.     

Determination of effective air-gap length of synchronous reluctance motors (SynchRel) from experimental data

The usage of synchronous reluctance motors (synchRel) has been gaining importance in many industry applications mainly because of their many advantages over other motors. The performance of a synchRel is greatly dependent on its effective air-gap lengths along the d and q axes. Hence, in this paper, an attempt has been made to obtain the effective air-gap lengths of the machine from the experimental values of the d and q axes reactances and by considering the higher permeance and winding space harmonics. To determine the air gaps, these reactances are compared with their corresponding expressions involving the coefficients of magnetizing and mutual inductances of the stator windings, obtained by using the winding function approach (WFA). Using these air-gap values, a more realistic model of the machine is obtained. A comparative study has been carried out with different permeance and winding space harmonics. The computed q-axis air-gap length seems to be much more sensitive to the operating point and the leakage inductance, compared to the computed d-axis air-gap length. Experimental values near the no-load condition have been considered to minimize flux barrier effects, as WFA cannot simulate these effects without changing the length of the pole arc. The effective air gaps of another salient-pole synchronous machine with damper bars have also been determined by considering the higher permeance and winding space harmonics, when run as a synchRel (without field excitation). This machine did not have flux barriers, and, hence, the results seem to be more accurate. Finally, the performance of the simulated synchRel has been compared with the experimental results.     

直流发电机与同步发电机交轴电枢反应的比较研究

主要解释了现行电机学书籍中关于直流发电机和同步发电机交轴电枢反应的差异.通过引入有效磁通的概念,理清了电机学中每极磁通概念的混乱;通过引入视在磁通的概念,使交轴电枢反应的效应在直流发电机和同步发电机中统一起来,维护了电机学内在的逻辑一致性.     

表贴式永磁同步电机空载磁场的解析计算

提出了一种解析法用于对表贴式永磁同步电机(SMPMSM)的空载磁场进行定量计算。基于子域模型法的理论,将定子开槽的气隙结构划分成定子槽子域和气隙子域,并且在子域中建立相应的拉普拉斯方程。根据子域与铁心间的边界条件以及子域间交界面上的连续条件,对拉普拉斯方程进行求解,从而可对开槽效应进行解析计算,得到相对复磁导函数。该相对复磁导函数不仅计及槽与槽之间的影响,还考虑了槽深的影响。基于所推导的相对复磁导函数,对SMPMSM的气隙相对磁导和空载磁场的径向以及切向分量进行计算。解析计算结果与有限元结果进行对比,验证了该相对复磁导函数的准确性。     

A Novel Dual-Stator Hybrid Excited Synchronous Wind Generator

This paper presents a novel dual-stator hybrid excited synchronous wind generator and describes its structural features and operation principle. The no-load magnetic fields with different field currents are computed by 3-D finite-element method. Static characteristics, including the flux-linkage and EMF waveforms of stator windings, and inductance waveforms of armature windings and field winding, are analyzed. The simulation results show that due to the dual-stator structure, the air-gap magnetic flux can be easily controlled, while the output voltage can be increased effectively. Tests are performed on the prototype machine to validate the predicted results, and an excellent agreement is obtained.      

Modeling of the armature slotting effect in the magnetic field distribution of a linear permanent magnet motor

A method for modeling the armature slotting effect of the magnetic field distribution in the air-gap region of a linear, permanent-magnet motor with armature slots is proposed. By using the concept of permeance, and using the 2-D finite element analysis and curve-fitting method, the relative permeance function of the armature slotting effect is expressed as a function of the motor's geometric parameters. The feasibility of the proposed model is verified by comparing finite element analysis and experimental results for a prototype motor. By using this proposed model, we can perform iterative work such as optimal design with quicker prediction of motor performance. Received: 23 October 2001/Accepted: 24 October 2001     

复合励磁稀土永磁同步发电机辅助电励磁部分的研究与设计

复合励磁稀土永磁同步发电机是一种能解决永磁发电机电压调节问题的新型发电机。该发电机转子由永磁发电机部分和辅助电励磁部分组成,它们共有一个电枢绕组。辅助电励磁部分采用爪极式结构,与永磁体同轴向,通过调节其磁场可调节输出电压,以达到稳定端电压的目的。探讨了该发电机辅助电励磁部分的基本结构和设计方法。实验分析表明,该辅助电励磁部分具有良好的调压功能,能实现端电压的稳定输出。     

复合励磁稀土永磁同步发电机辅助电励磁部分的研究与设计

复合励磁稀土永磁同步发电机是一种能解决永磁发电机电压调节问题的新型发电机。该发电机转子由永磁发电机部分和辅助电励磁部分组成，它们共有一个电枢绕组。辅助电励磁部分采用爪极式结构，与永磁体同轴向，通过调节其磁场可调节输出电压，以达到稳定端电压的目的。探讨了该发电机辅助电励磁部分的基本结构和设计方法。实验分析表明，该辅助电励磁部分具有良好的调压功能，能实现端电压的稳定输出。     

三相感应励磁发电机的运行性能及磁势感应系数

本文研究了三相倍极感应励磁同步发电机中倍极静止磁场的存在对电机运行性能的影响，并引入了反映定子直流绕组感应产生转子主励磁磁势能力的磁势感应系统这一重要概念。结果表明：采用倍极感应励磁对电机的运行性能无明显不良影响，但由于磁势感应系数较低，所需定子直流绕组安匝数较大，导致电机主绕组容量下降较多。文中分析了造成磁势感应系数低的原因，探讨了改善途径。     

径向充磁圆筒永磁直线同步电机磁场和推力解析计算

介绍了一种基于标量磁位分离变量法(圆柱坐标)的径向充磁圆筒永磁直线同步电机磁场解析计算方法。利用该解析法理论分析了无槽电机的气隙磁场,得到了气隙磁场的轴向和径向磁场分布的解析结果;同时对有槽电机引入了卡特系数并利用许-克变换构造了考虑齿槽效应的气隙相对比磁导函数,得出了径向磁通密度的解析表达式;此外,文中还利用解析法计算了无槽电机的推力;通过有限元数值算法对磁场和推力进行计算,结果表明,该电机气隙磁场及电磁推力的两种计算方法的结果误差很小,验证了解析法的正确性和实用性。最后给出了无槽型实验样机的径向磁场分布以及电机额定负载时的推力实验结果,验证了样机分析和设计的正确性。     

不同转子结构的永磁半直驱同步风力发电机电磁场的计算与分析

以1.5MW永磁半直驱式同步风力发电机为研究对象,设计了定子252槽、转子32极、永磁体在转子嵌放位置不同的发电机方案,建立电磁场二维有限元计算模型。分别给出两台风力发电机空载和负载两种工况下的磁场波形,并给出两台电机各取一个单元电机内的负载径向气隙磁密谐波分解图,同时计算了负载时绕组磁动势的谐波含量。此外,对相同类型结构的小型永磁同步风力发电机的实测数据与理论计算结果进行比较,为设计大容量永磁半直驱风力发电机提供了一些有意义的参考。     

宽调速可控磁通永磁同步电机磁路设计和有限元分析

提出了一种内置混合式转子可控磁通永磁同步电机,是真正意义上的宽调速电机.其径向永磁体采用剩磁密度和矫顽力都很高的钕铁硼,而切向永磁体采用剩磁密度高但矫顽力却很低的铝镍钴.通过定子直轴电流矢量脉冲控制铝镍钴的磁化方向和强弱,使钕铁硼产生的磁通部分穿过气隙,部分被铝镍钴在转子内部旁路,使永磁气隙主磁通受控.给出了永磁体尺寸和磁路结构尺寸的选取原则,特别是将交轴磁路磁阻设计的较大,交轴电感较小时,弱磁效果会更好,还能减少电枢反应对永磁气隙主磁通的影响.对两种极端磁化状况下模型电机内部磁场的分布进行了有限元分析,说明所提出的设想是可行的.     

考虑饱和效应凸极同步电动机矢量控制

通过闭环复合磁链观测器,可获得优良的气隙磁链观测效果.基于此,提出一种考虑饱和效应的凸极电机数学模型,利用DSP2812为核心的同步电机实验平台,完成了同步电机矢量控制实验.实验结果表明,基于所提出的气隙磁场定向矢量控制系统具有高性能动静态特性,利用此处建立的饱和数学模型分析和控制同步电机,在磁场饱和非线性时,同步电机...     

双定子高温超导电机阻尼绕组对超导励磁磁场及电枢反应磁场作用机理分析

基于静态密封双定子高温超导电机（DS HTSM）中的静止气隙磁导模型,采用理论公式与有限元仿真相结合的方法分析阻尼导条对磁场的影响。按照磁力路径推导出内气隙磁密,通过建立等效阻尼电路模型,得到其在超导线圈附近感应的反交流谐波,通过有限元仿真进行验证。分析结果表明,鼠笼式阻尼导条可以在基本不影响DS HTSM励磁磁场的同时,削弱基波电枢反应磁场对超导线圈的影响。